At present, there are a variety of connectionless and connection-oriented transmission methods which are used for rapidly transmitting data packets via a communication network.
The so-called MPLS (multiprotocol label switching) method is used as a connectionless transmission method where an acceleration of the transmission of so-called IP data packets based on the Internet protocol (IP) is to be achieved. In this method, so-called label switching routers (LSR) are provided which can transmit IP data packets at high speed along a route consisting of label switching routers. A conventional router based on the Internet protocol must compare a destination IP address of a received IP data packet with entries in its routing table in order to determine, via a so-called longest match, the link via which the IP data packet is to be forwarded. A label switching router, in contrast, receives the IP data packet together with a prefixed label and uses this label as table index in order to take from a table the information for identifying the link for forwarding the IP data packet and a new label which is forwarded together with the IP data packet instead of the received label. In this manner, IP data packets can be forwarded much more rapidly.
FIG. 1 illustrates a setup message for an ATM connection in the form of a so-called μ setup message ATMZ according to the prior art. The μ setup message ATMZ has a 48-byte-large payload area which is shown in 6 rows in each case comprising 8 bytes. Data field T contains an information element defining the type of the ATM cell, data field Q contains a connection parameter by means of which individual characteristics of the connection to be set up are specified, data fields NSAP contain the address of the destination network node, data field PID contains a so-called protocol identifier and data field VPI/VCI contains a proposed value for the so-called virtual path identifier VPI and the so-called virtual connection identifier VCI for the ATM cells to be transmitted in the useful data connection to be set up.